Intervention rates should be interpreted in the context of perinatal morbidity, not just mortality

Jeremy J Chin, Obstetrics and Gynaecology Trainee

Monash Medical Centre

Dahlen's study, "Rates of obstetric intervention among low-risk women
giving birth in private and public hospitals in NSW: a population-based
descriptive study" provides a useful window into contemporary midwifery
and obstetric practice in Australia. It is unfortunate that the authors
choose to discuss the rising rate of intervention in low-risk women in
both private and public settings in the context of a static perinatal
mortality rate, rather than the discrepancies of, for example, maternal
perineal trauma ('severe perineal trauma' and 'third degree tear') and
early neonatal condition following birth ('APGAR score <7 at 5 min'),
both of which are lower in women birthing in the private setting.
Australia's enviously low perinatal mortality rate surely means that a
more nuanced approach to intervention rates in low-risk women include a
fuller account of maternal and perinatal morbidity, not just perinatal
mortality.

Conflict of Interest:

Private Obstetrics - again

Robert G Buist, Obstetrician

Rob Buist Obstetrics

This paper by Dahlen et al has reignited the public debate about
obstetric intervention rates in Australia.
Strangely - given the size of the dataset available to the authors -
adverse perinatal outcomes were not examined in the study. However in the
discussion the authors assert "these (higher) rates do not appear to be
parallel to or be associated with a better infant outcome" and go on to
cite a small single centre RCT of case loading midwifery in support of
their assertion.
The authors failed to cite or discuss a large population based study -
again from Australia - that demonstrated a higher prevalence of adverse
perinatal outcomes in public hospitals than in private hospitals between
2001 and 2004. After adjusting for multiple risk factors the study (Robson
SJ et al, Med J Australia 2009; 190(9): 474 -7)found that the adjusted
odds ratios (AORs) for a higher level of resuscitation and perinatal death
were 2.37 (95% CI 2.17 - 2.59)and 2.02 (95% CI 1.78 - 2.29)respectively.
I find it disappointing that Dahlen et al could not cite or discuss the
Robson study given its contemporaneous nature and degree of relevance to
their own study. An unkind interpretation would be that the authors have
selectively used statistics in order to influence public debate in
Australia.

Conflict of Interest:

Conclusion on the impact of interventions is not supported by data in the paper

Amy Tuteur, MD, obstetrician

self employed

Dahlen et al. claim:

"The continual rise in obstetric intervention for low-risk women in
Australia is concerning in terms of morbidity for women and cost to the
public purse. The fact that these procedures which were initially life-
saving are now so commonplace and do not appear to be associated with
improved perinatal death rates demands close review."

However, the authors never looked at the perinatal death rate in the
population that they studied so they cannot determine the impact of the
interventions they decry. Although they looked at intervention rates in a
low risk population (124,431 women), they compared them to mortality rates
in the overall population including high risk women, prematurity and all
complications of pregnancy (691,738 women).

Even then, the authors do not accurately represent the trend in
perinatal mortality in NSW over time.

The authors state:

"The NSW rate of perinatal mortality was between 8.6 and 9.6 per 1000
births between 2000 and 2005 and between 8.7 and 9 per 1000 births between
2005 and 2009."

While this is true, a more accurate representation is that from 2000-
2008 overall perinatal mortality in New South Wales dropped from 9.7/1000
to 8.7/1000, a drop of 10% (1,2).

This study tells us only the trend of intervention use among low risk
women in NSW from 2000-2008 and the difference in intervention rates
between low risk women in private and public hospitals. There is no
information presented that would allow us to draw conclusions about
whether the interventions were used appropriately or whether they led to a
decrease in perinatal mortality.